Eclipses don't happen every month because usually the Sun, Earth and Moon aren't quite lined up. The Moon’s orbit is slightly tilted with respect to Earth’s orbit. The orbits cross at two points called nodes. If a full moon or a new moon occurs at these nodes, only then are the three bodies lined up for an eclipse.

The Moon orbits the Earth in 27 days, but it takes 29.5 days to get from new moon to new moon. Since the Earth is also moving in its orbit, the Moon need extra time to complete its cycle of phases.

Lesson plans
Click on the link to access the material.

(1) Educator's Guide to Moon Phases. The Jet Propulsion Laboratory has prepared this simple, but useful, activity. It recognizes some of the pitfalls in teaching the topic, though you may find that getting the classroom dark enough is your biggest headache. (If so, it's worth negotiating with colleagues to try to get somewhere suitable.)

(2) The Lunar and Planetary Institute. There are a number of activities here. For each one you are told for which age range it is suitable, the time and materials required, and how to run the lesson.

There is a basic lesson in which the children are asked to observe and record moon phases by actually looking at the sky. Hurrah! "Fruit for Phases" is the same idea as the JPL activity and could be done with or without "The Girl Who Married the Moon." Using the story could work nicely in a primary classroom if you are planning cross-curricular work.

If you want to include eclipses, consider "Fruit Loops: Exploring our Moon's Phases and the Reason for Eclipses." Do use the hoops or rings. They're essential to show that the orbit of the Earth and the Moon are tilted with respect to each other, which is why we don't have eclipses every month.

Other resources
(1) Lunar Phases. This takes the learner through three activities to understand the phases of the Moon. It's very good.
(2) Earth and Moon Viewer. This page shows the current moon phase. If you want to change the date, time or place, scroll down the page.
(3) Here's an extension activity to (2). Apollo 11 astronaut Michael Collins used to have a little picture of a crescent-shaped body on his wall. Even though the coloring was wrong, people identified it as the Moon. It was the Earth. See the current phase of the Earth as viewed from the Moon. How are the phases of the two bodies related?
(3) Enchanted Learning. Printable worksheets with diagrams to label of solar eclipses and lunar eclipses Suitable for Grades 7-8.
(4) NASA Starchild. An online quiz to identify and order Moon phases.

My Pinterest boards Eclipses and The Moon contain images related to this article.